Pavement surface treating apparatus

ABSTRACT

A pavement surface treating process for renewing or roughing the pavement surface to prevent vehicles running along the pavement from slipping by forming fine concaves and convexes on the pavement surface with vertically movable roughing elements and a pavement surface roughing apparatus movable along the pavement including a vertically movable roughing mechanism which has pavement surface roughing elements adapted to strike against the pavement surface to form uneven surface areas thereon.

United States Patent 191 Makishima Dec. 3, 1974 v [5 PAVEMENT SURFACE TREATING 1,745,100 1/1930 Johnson et al..l 299/37 x APPARATUS 1,997,248 4/1935 Densberger 172/612 X Rl1,l36 12/1890 Bryant .1 299/38 [76] Inventor: Sumio Makishima, 67-3 Shinmachi Tokyo Japan Primary Examiner-Ernest R. Purser [22] Filed: Jan. 4, 1973 Attorney, Agent, or FirmOblon, Fisher, Spivak,

Appl. No.: 320,864

Foreign Application Priority Data Jan. 14, 1972 Oct. 23, 1972 Japan 47-105331 US. Cl 299/37, 172/612, 299/94 Int. Cl. E01c 23/09 Field of Search 299/37, 38,94, 10-18;

References Cited UNITED STATES PATENTS 7/1904 Ciralli 29 9/37 Japan 47-5818 McClelland & Maier [5 7 ABSTRACT A pavement surface treating process for renewing or roughing the pavement surface to prevent vehicles running along the pavement from slipping by forming fine concaves and convexes on the pavement surface with vertically movable roughing elements and a pavement surface roughing apparatus movable along the pavement including a vertically' movable roughing mechanism which has pavement surface roughing elements adapted to strike against the pavement surface to form uneven surface areas thereon.

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W M //J PAVEMENT SURFACE TREATING APPARATUS BACKGROUND OF THE INVENTION This invention relates to a pavement surface treating or roughing process for prevention of slippage of vehicles thereon and an apparatus for carrying out the process which includes a plurality of vertically movable roughing elements which move into impact delivering contact into or away from the pavement surface.

Generally, an asphalt pavement comprises a base layer, a bituminous concrete intermediate layer and a surface layer which includes a mixture of cement and sand, fine mineral filler or aggregate such as cement. According to the prior art processes for roughing the surface of such an asphalt pavement, when the pavement has worn away to the degree that the surface of the pavement has become slippy, the aggregate in the surface layer is suitably exposed to the pavement surface so as to increase the coefficient of friction of the surface thereby to enhance the frictional resistance of the pavement surface and prevent the possibility for slippage of vehicles thereon. However, on a heavy traffic road, an area adjacent to a road crossing or a curve, the aggregate in the surface layer rapidly wears away or tends to bury underneath the pavement surface so as to present a slippery surface to the pavement which may cause traffic accidents.

There has been proposed and practically employed a number of countermeasures for preventing slippage on such pavements as follows: I

1. A pavement renovation machine such as a motordriven grader or road dresser which shaves off worn or slippery surface areas from the pavement and renovates the pavement. This process is referred to as the pavement renovation process. However, this process has the disadvantage that the process requires a great deal of workers and thus is expensive.

2. Slippage prevention grooves are cut in the worn surface of a pavement. However, this process has the disadvantage that a great amount of aggregate has to be removed from the pavement surface resulting in an increase of cost per unit area.

3. A slippage prevention mixture material is applied onto the worn or slippery surface of a pavement. In such a case, the mixture comprises synthetic resin, quartz and alumina. However, this process also has the disadvantage that the application of such a mixture requires a great deal of workers and time.

4. The worn or slippery surface of a pavement is eroded with a chemical to make the surface uneven or rough to the extent that slippage is prevented on the pavement surface. However, this process has the disadvantage that it must take a prudent care in handling such a chemical and the eroded surface is not durable. In addition, the erosion requires a'substantially long period of time.

SUMMARY OF THE INVENTION a pavement surface treating process and apparatus to efficiently expose the aggregate at less expense depending upon the pavement conditions such as the abrasion degree, hardness of the pavement and the like.

A further object of the present invention is to provide a process and an apparatus which can be employed regardless of weather conditions in the formation of a slippage prevention surface on a pavement without the obstruction of other vehicles as much as possible, even on a heavy traffic pavement.

A still further object of the present invention'is to provide a process and an apparatus for forming a slippage prevention pavement surface easily and rapidly.

A further object of the present invention is to provide a process and an apparatus which can form coarse recesses in the worn surface of a pavement by the employment of a novel roughing mechanism.

A still further object of the present invention is to provide a process and an apparatus which can form a rough pavement surface which has an appearance similar to that formed by a fine sand paper.

The above and other objects and attendant advantages of the present invention will be more readily apparent to those skilled in the art from a reading of the following detailed description of the same in conjunction with the accompanying drawings which show preferred embodiments of the invention for illustration purpose only, but not for limiting the scope of the same in any way.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a schematic side elevational view of a first embodiment of pavement surface treating apparatus constructed in accordance with the present invention;

FIG. 2 is a fragmentary plan view as shown in the line II II of FIG. 1;

FIG. 3 is a cross-sectional view on an enlarged scale taken along substantially the line III III of FIG. 2 especially showing the replaceable pavement surface roughing mechanism of FIG. 1;

FIG. 4 isa fragmentary perspective view of a modifled form of replaceable roughing mechanism useful in said pavement surface treating apparatus of FIG. 1;

FIG. 5 is a fragmentary view of a still further modifled form of pavement surface roughing mechanism;

FIG. 6 is a side elevational view of a second embodiment of pavement surface treating apparatus constructed in accordance with the present invention;

FIG. 7 is a front elevational view of said pavement surface treating apparatus as shown in FIG. 6;

FIG. 8 is a sectional view taken along substantially the line VIII VIII of FIG. 7 especially showing the pavement surface roughing mechanism as shown in the Figure;

FIG. 9 is a perspective view of said roughing mechanism of FIG. 8;

FIG. 10 is a schematic diagram showing loci described by the lower ends of piano wires employed in the pavement surface roughing mechanism of FIG. 9 as the mechanism is operated;

FIGS. 11 and 12 are operative views showing varying operations in different mounting positions and warping states of the piano wire roughing elements;

FIG. 13 is a side elevational view of a third embodiment of pavement surface treating apparatus constructed in accordance with the present invention;

FIG. 14 is a fragmentary side elevational view on an enlarged scale of the portion A as shown in FIG. 13 with portions thereof broken away;

FIG. 15 is a fragmentary vertically sectional view of a section of the portion A of FIG. 13 on a further enlarged scale;

FIG. 16 is a view taken substantially along the line XVI XVI of FIG. 14;

FIG. 18 is a perspective view on an enlarged scale of a modified form of roughing element employed in the embodiment of FIG. 13;

FIG. 17 is a view showing the striking or downward stroke of the roughing mechanism of the embodiment of FIG. 13;

FIG. 19 is a sectional view ofa section of a pavement before the same is treated by any of the pavement surface treating apparatus of the invention; and

FIG. 20 is a sectional view of a section of said pavement of FIG. 19 after the same has been treated by any of the pavement surface treating apparatus of the invention.

PREFERRED EMBODIMENTS OF THE INVENTION The present invention will be now described referring to the accompanying drawings and more particularly, to FIGS. 1 through inclusive in which the first embodiment of pavement surface treating apparatus of the invention is illustrated. In FIG. 1, reference numeral 1 denotes the main body of the pavement surface treating apparatus and the main body is provided at the inner end portion with an attachment element 4 for connection with the inner end portion of a tractor 3 which is in turn mounted on a light duty vehicle 2 which moves the pavement surface treating apparatus along a pavement. The apparatus has at the outer end portion a pair of laterally spaced steering wheels 5 and 5 which are mounted on the main body 1 for vertical movement by suitable conventional means. The main body incorporates therein a power transmission mechanism which is generally shown with reference numeral 6. The power transmission mechanism 6 generally comprises a crank 8 which is mounted on a rotary shaft 7 substantially in the center of the length of the latter and a connector bar 9 connected to the crank. The rotary shaft 7 further has a pulley I0 adjacent to one end of the shaft and trained over the pulley is a V-belt 13 which is also trained over a pulley 12 which is in turn mounted at one end of the output shaft of an engine 11 mounted on the tractor 2 so that the rotational movement of the engine shaft is transmitted through the pulley-belt drive arrangement to the crank 8 which in turn rocks the connector bar 9 back and'forth.

Although the crank mechanism is employed as the power transmission mechanism in the illustrated embodiment, other types of power transmission mechanism such as a cam mechanism, linkage and fluid motor or any suitable drive mechanism can be also employed within the scope of the invention. A roughing mechanism drive mechanism 14 is suitably mounted within the main body 1 substantially in the center of the latter and the drive mechanism generally comprises a stationary shaft 15 parallel to and spaced from the rotary shaft 7, a sleeve 16 rotatably mounted on the shaft, an arm 17 vertically and upwardly extending from the center of the shaft 15, a pair of arms 18 and 18 vertically and downwardly extending from the opposite ends of the sleeve and a pair of horizontal arms 19 and I9 exte nding from the opposite ends of the sleeve at right angles to the latter. Each of the arms 19 has an outer free end portion 20 which extends downwardly at substantially right angles to the main portion of the associated arm 19 and has at its extreme lower end a pavement surface roughing mechanism 22 fixedly mounted thereto. The roughing mechanisms 22 will be described in detail hereinafter.

The lowermost ends of the downwardly extending arms 18 may be selectively connected to any one of pavement surface striking mechanisms 39 and 44 which will be described hereinafter by means of suitable fastening means 23 and 23 as the case may be. The alternate roughing mechanisms 39 and 44 will be in detail described referring to FIGS. 4 and 5 hcreinbelow. The upwardly extending arm 17 has a hollow connector bar receiving means 24 adjacent to the uppermost end thereof and the bar receiving element has a threaded inner or base portion for threaded engagement with an adjusting screw 25 which is received in the hollow upper portion of the associated arm so that by turning the screw in one or the other direction, the height of the connector bar 9'may be varied so as to vary the amplitude of the movement of the roughing mechanism 22. For the purpose, the arm 17 is provided with a slot (not shown) in the upper portion thereof for guiding the means 24.

Referring now to FIG. 3 of the accompanying drawings, there is shown a first embodiment of pavement surface roughing mechanism 22 of the invention and as shown in this figure, the roughing mechanism 22 gene rally comprises a pair of parallel and spaced upper and lower steel support plates 27 and 28 which are connected together by means of a plurality of fastening means 26, 26 which extend vertically between the upper and lower plates and a plurality of chisels 29, 29 which are loosely received in the corresponding aligned holes in the upper and lower support plates 27 and 28 for vertical reciprocal movement. As shown in FIG. 3, each of the chisel 29 has a bulged portion between the opposite ends thereof which is larger in diameter than the holes in the support plates so that the chisel can be prevented from coming out of the aligned holes while the same is allowed to freely move through the holes. The upper support plate 27 has a pair of upwardly extending projections 30 and 30 for connection with the lowermost ends 20 of the arms 19 by means of the afore-mentioned fastening means 21. As more clearly shown in FIG. 2, the upper and lower support plates 27 and 28 have a rectangular shape having the longer sides extending transversely of the longitudinal axis of the main body and the shorter sides extending in parallel to the longitudinal axis. The opposite ends or shorter sides of the upper and lower support plates 27 and 28 are provided substantially in the center with aligned notches 33 and 33 for engaging guide rails 32 fixedly mounted on the inner surfaces of side frames 31 and 31 of the main body 1 to be guided along the rails to that the upper and lower plates can vertically move in unison relative to the main body.

Each of the chisels 29 has a pointed tip 34 which projects downwardly through one of the holes 35 in the lower plate 28 and a non-pointed upper end 36 projects upwardly through one of the holes 37 in the upper plate 27. A coiled spring 38 is disposed on each chisel 29 with one end abutting against the underside or inner side of the upper plate 27 and the otheriend abutting against the bulged portion of the associated chisel so as to normally urge the chisel 29 downwardly. Numeral 49 in FIGS. 1 and 2 denotes a conventional rotary cleaning brush which is rotated from the rotary shaft 7 through a transmission mechanism comprising a bevel gear train 50 and a pulley belt arrangement.

According to the present invention, if necessary or desired, the pavement surface roughing mechanism 22 may be replaced by either one of the modified pavement surface roughing mechanisms 39 or 44 as shown in FIG. 4 and FIG. 5, respectively, within the scope of the present invention depending upon particular pavement conditions.

Referring to FIG. 4 which shows the first modified embodiment of pavement surface roughing mechanism 39 and the modified roughing mechanism generally comprises a base framework 40 including three parallel and spaced longer frame members and two parallel and spaced shorter frame members which connect the longer frame members together at their opposite ends.

Each of the longer frame members has a plurality of equally spaced pawls 41 extending downwardly therefrom. The pawls 41 on one frame member are in a staggered relationship to those on the adjacent frame member. A pair of spaced L-shaped attachment elements 42 and 42 are provided on the base framework 40 with their horizontal portions secured to the longer frame members and the upright portions 43 projecting out of the adjacent one frame member for connection with the arms 18. Referring to FIG. 5 which shows the second modified embodiment of pavement surface roughing mechanism 44 which generally comprises an oval cross-section roller 45 having a plurality of spaced wedge-shaped projections 46, 46 in the periphery, and a pair of L-shaped attachment elements 47 and 47 are provided with their horizontal portions pinned to the opposite ends faces of the roller and the upright portions 48 projecting at right angles to the horizontal portions for connection with the arms 18 by means of the afore-mentioned fastening means 21.

In operation, when the engine 11 is rotated, the rotational movement of the engine is transmitted through the output shaft of the engine, pulley l2, V-belt 13 and power transmission mechanism 6 to the rotary shaft 7 which in turn rotates the crank 8 which moves the connector bar 9 back and forth. The movement of the connector bar 9 causes its arm 17 to pivot about the shaft back and forth and at the same time, to move the arm 19 upwardly and downwardly and the arm 18 back and forth about the shaft 15, respectively.

The pavement surfacestriking mechanism 22 which is connected to the lower ends 20 of the arms 19 rocks upwardly and downwardly about the shaft 15 describing an arc to cause the pointed tips 34.0f the chisels 29 to strike against a pavement surface with a light impact. When the pavement surface roughing mechanism 22 is replaced by the modified roughing mechanism 39 as shown in FIG. 4, the tips of the pawls 41 strike against the pavement surface from above at an oblique angle to the surface describing an are about the shaft 15. Similarly, when-the second modified form of pavement surcontinuously performed on the pavement surface as the tractor 2 to which the pavement surface treating apparatus which selectively employs one of the three alternative strikingmechanisms is connected, successive sections of the pavement can be successively treated.

In the foregoing, it has been described in conjunction with the case wherein the light duty tractor 2 is employed as the means for transporting the entire pavement surface treating apparatus, but it is to be understood that a heavy duty tractor, truck or the like transporting vehicle can be selectively employed as the transporting means within the scope of the invention.

When the afore-mentioned pavement surface treating is operated, the plural chisels, pawls or projections can simultaneously form a plurality of recesses in the pavement surface by striking against the surface with a slight impact. When the pavement is an asphalt paved road which has the asphalt surface layer with a high density due to wear or undersurface burying of aggregate, the asphalt surface layer is broken open to expose the undersurface aggregate to the surface whereby the surface will have an increased coefficient of friction. If

,the number of the chisels, pawls or projections is increased and the tips of the roughing elements are more sharpened, the white and/or yellow demarcation lines marked on the particular surface of a road section can be easily erased and the roughness on the pavement surface can be improved. When the novel pavement surface treating apparatus is employed on a concretepaved road having a worn surface or recesses clogged with debris of rubber from tires, the worn or rubberclogged surface can be restored to its original desired rough road surface state having a proper high coefficient of friction to the extent that slippage of vehicles on the road can be effectively prevented.

Furthermore, the pavement surface treating apparatus of the invention can be transported to any desired location by means ofa vehicle such as a light duty truck and operated with a minimum number of workers without requiring any additional material or means to restore a particular pavement to its desired slippage prevention rough state. Thus, by the employment of the novel pavement surface roughing apparatus, a particular pavementcan be restored to its desired original rough surface state at a relatively less expense than by the conventional apparatus. The novel apparatus is especially suitably employed on highways to maintain the highways at a desired high coefficient of friction thereby to greatly contribute to prevent of occurrence strike against the surface of a particular pavement to face roughing mechanism 44 which may be also connected to the arms 18 is employed, the projections 46 strike against the pavement surface from above at an oblique angle to the surface describing an are as the roller 45 rotates. The above-mentioned operation is rough the surface.

In these figures, reference numeral, 51 generally denotes the pavement surface roughing mechanism and reference numeral 53 denotes the framework of the pavement surface treating apparatus. The treating apparatus 53 is suitably connected to a tractor 52 to be transported thereby and has steering wheels 54 which support the framework 53 to allow the framework to ,move upwardly and downwardly in conformity with the contour of the surface of a particular pavement to be treated as the treating apparatus is moved along the pavement. The horizontal top 55 of the framework 53 mounts a transverse shaft 56 for rotation and an eccentric annular shaft 57 is mounted on the transverse shaft. The eccentric shaft 57 is supported in a bearing 58 which is integrally formed with the top of the roughing mechanism 51 so that the mechanism is suspended from the .eccentric shaft 57. The end walls 59 of the roughing mechanism 51 have substantially in the center connector rods 60 pivoted thereto and the other ends of the connector rods are connected by means of members to the tractor as will be described hereinbelow. The end walls 59 are formed with a plurality of threaded holes'6l which are selectively employed and connector rods attachments 63 having stub shafts projecting outwardly are secured to the end walls by means of bolts 62 which are threaded into selected ones of the threaded holes .61. The ends of the connector rods 60 are pivoted to the stub shafts of the attachments 63. Thus, it will be noted that by selecting a different group of threaded holes 61, the position of the connector rods 61 relative to the roughing mechanism can be varied. The other ends of the connector rods 60 are pivoted to stationary stub shafts 64 integrally formed with the framework 51.

The pavement surface roughing mechanism l ineludes a lower horizontal guide plate 66 having a plurality of spaced through holes 65 therein and fixedly secured to the end walls 59 and an upper horizontal guide plate 67 in parallel to and spaced above the lower guide plate and having a plurality of through holes 71 in alignment with those in the lower guide plate. The position of the upper guide plate 67 can be adjusted relative to the lower guide plate in a manner as will be described hereinbelow. The upper guide plate 67 has threaded holes at its four corners for receiving bolts 68 which pass through selected ones of the threaded holes 70 in the edges 69 of the end walls 59. Thus, it will be understood that by selecting a different group of threaded holes 70, the position of the upper guide plate 67 can be varied relative to the lower guide plate 65. The through holes 71 in the upper guide plate 67 have a diameter slightly smaller than that of the through holes in the lower guide plate 65. Resilient steel wire or piano wire sections or pavement surface roughing elements 72 extend through and are guided by the aligned holes 65 and 71 in the lower and upper guide plates 66 and 67 with the lowermost ends 72' projecting downwardly of the lower guide plate 66 and lying in substantially the same plane. As shown in H6. 8, each of the steel wire sections 72 is folded at the uppermost end 72 where the wire seetion is secured by means of elements as will be described hereinbelow to an anchoring member 74 which isin turn fixedly secured to the top of the roughing mechanism 51. The securing elements inelude angles 77 secured to the top edges 75 of the end walls 59 by means of bolts 76 and shafts 78 which horizontally extend between the angles 77 in a parallel and spaced relationship to each other. Thus, it will be noted that each steel wire section 72 has two downwardly extending and parallel legs which pass through each adjacent two through holes 65 and 71, respectively, in the lower and upper guide plates 66 and 67. The top edges have slots therein for receiving the bolts 76 and by loosening the bolts, the position of the angles 77 can be varied relative to the top edges 75. The wire sections 72 are maintained in a predetermined spaced relationship to each other by means of spacers 79 which are fixedly mounted on the shafts 78 at spaced points therealong. ln FlGS. 6 through 12 inclusive, reference numerals 80, 81, 82, 83, 34, 85, 86 and 87 denote pul leys, an engine, V-belts, a rotary cleaning brush and bearings, respectively.

In the operation of the second embodiment of pave ment surface treating apparatus of the invention, when the engine 83 is rotated. the rotational movement of the engine is transmitted through the pulley 82, Vbelt 85, pulley 81 and \/-belt 84 to the rotary shaft 56 which in turn rotates the eccentric shaft 57. As the eccentric shaft 57 rotates, the upper portion of the roughing mechanism 51 rocks in conformity the eccentricity of the eccentric shaft 57 describing an arc and at the same time, the connector rods 60 reciprocally pivot about the shafts 64 whereby the lower portion ofthe roughing mechanism 51 rocks describing an arcuate locus similar to that described by the upper portion, but in the direction opposite to that in which the upper portion rocks. When the lower portion of the roughing mechanism 51 reaches the lowermost portion of its arcuate locus movement. the tips of the steel wire sections 72' strike against the surface of a pavement to be treated to rough the surface. The radius of the imaginary circle described by the rocking movement of the lower portion of the roughing mechanism 51 can be varied by moving the mounting position of the connector rod attachments 63 relative to the end walls 59. By repeating the operation cycle described above as the pavement surface treating apparatus is moved along the particular pavement by the vehicle such as the tractor 52, the tips 72 of the steel wire sections 72 describe the loci as shown in FIG. 10 depending upon the mounting position of the connector rod attachments 63 on the end walls 59.

In FlG. 10, line 0 represents the locus described by the lower portion of the roughing mechanism 51 when the rod attachments 63 are mounted in the uppermost possible position, line b represents the locus described by the same portion of the roughing mechanism when the rod attachments are mounted in an intermediate position and line c represents the locus described by the same portion of the roughing mechanism when the rod attachments 63 are mounted in the lowermost possible position. Furthermore, in H6. 10, reference character d represents the advancing direction of the pavement surface treating apparatus and e represents the length of the portion of each wire section which projects downwardly of the lower guide plate 66. The mounting position of the rod attachments 63 can be suitably selected depending upon the hardness and/or worn state on the surface of a particular pavement to be treated and the impacting force of the stell wire sections 72 can be varied in accordance with the selected mounting position of the rod attachments 63.

Referring to H0. 11, according to the present invention, the pressure P generated in the wire sections 72 when they strike against the pavement surface can be varied by the utilization of bending stress in the portions of the wire sections 72 extending between the wire anchoring member 74 and adjustable guide plate 67 whereby the component of a force F acting on the wire sections in the bending direction can be varied.

Referring to FIG. 12 in which a modified arrangement of the through holes 65 and 71 in the lower and upper guide plates 66 and 67 is shown. As seen in this figure, the through holes in one of the two guide plates are respectively staggered with respect to the respectively associated through holes in the other guide plate sothat the wire sections extend through the holes at an angle with respect to the vertical. With the arrangement of the through holes 65 and 71 as shown in FIG. l2, the flexing degree of the tips 72 of the wire sections 72 extending below the lower guide plate 66 at the time of their striking against the pavement surface may be changed so as to perform an optimum treatment on a particular pavement surface at any time. In the arrangement of FIG. 12, the length of the wire sections 72 extending between the wire anchoring member 74 and upper guide plate 67 can be changed so as to change the bending degree of the wire sections resulting in variation in the striking force of the wire sections against the pavement surface.

The roughing mechanism 51 in the embodiment of FIGS. 6 through 12 inclusive which comprises the roughing elements in the form of wire sections 72 is most suitably employed for treating roads paved with asphalt in that the roughing mechanism can remove excess asphalt from the pavement without exposing the aggregate lying beneath the surface layer to 'the surface. The roughing elements in the form of wire sections 72 are less expensive as compared with the chisel, pawl and projection arrangements as described hereinabove. Furthermore, since the wire sections 72 are freely adjustable for their striking state and striking force, the wire sections canbe suitably employed on pavements having different conditions. However, when theresilient wire sections 72 strike against the pavement surface with a frequency higher than their inherent frequency, there will be the possibility that they strike against the pavement surface in their warped state and in consequence, their striking force will be substantially decreased which makes it impossible to enhance thier operation efficiency to a desired high level. Therefore, it may be necessary to employ more tenacious resilient wire material for the roughing elements which leads to increasement in material expense and driving force and in consequence, the entire apparatus will inevitably have a larger size. Thus, it is desirable to provide a pavement surface treating apparatus which can enhance operation efficiency without the sacrifice of striking force even when the wire sections strike against the pavement surface with a frequency higher than their inherent frequency. Such an apparatus is shown in FIGS. 13 through 17 of the accompanying drawings.

Referring to FIGS. 13 through 17 inclusive, reference numeral 88 denotes the main'body of the pavement surface treating apparatus having stearing wheels 89 supporting the main body. As distinguished from the previous embodiments, the main body 88 mounts an engine 90 thereon and in consequence, the apparatus is a self-drive type. 91 denotes the crank of an oscillation means and is rotated from the engine 90 through a clutch 92 and V-belts 93 and 94. The crank shaft 95 of the oscillation means including the crank 91 has the pavement surface roughing mechanism 96 suspending therefrom. The roughing mechanism 96 is adapted to vertically oscillate as the crank rocks and has a box shape. The upper end of the roughing mechanism 96 is mounted on the crank shaft by means of a hanger member 97 and the lower end of the mechanism has stationary stub shafts 98 projecting out of the opposite sides thereof. Mounted pivotally on the stub shafts 98 are support arms 99 the other ends of which are pivotally mounted on a transverse shaft 100 extending between the opposite side frames of the main body 88. Therefore, when the crank shaft 95 is rotated, the lower end of the roughing mechanism 96 is caused to reciprocally move about the shaft 100 describing an arcuate locus. Roughing elements in the form of tenacious steel wire sections are provided in three rows each row including a plurality of wire sections 101 within the pavement surface roughing mechanism 96. Each row of the three rows of wire sections 101 are normally disposed at an angle with respect to the vertical and have the upper ends 101a wound about a transverse shaft 102 secured to the upper end of the mechanism and the lower ends 10lb extending downwardly through guide holes 102 formed in separate stub shafts 103 at the bottom of the mechanismThe stub shafts 103 are rotatably supported at the opposite bottom ends 105 of the mechanism 96 by means of bearings 106.

Warp control means 104 are provided above the respectively associated stub shafts 103 within the pavement surface roughing mechanism 96. The warp control means 104 are disposed between arms 107 fitted on the opposite ends'l03a of the shafts 103 at right angles to the arms and each of the warp control means 104 is provided with a plurality of through holes 108 through which the wire sections extend. The arms 107 have at the lower ends lateral projections 109 extending at right angles to the main bodies of the arms 107 and cooperating projections 110 are provided on the opposite side frames of the mechanism 96. Coiled springs 111 extending between and anchoed to the cooperating projections 109 and 110 which urge the projections 109 on the arms 107 against stops 112 provided on the side frames of the mechanism 96. The arms 107 are disposed at such an angle with respect to the vertical that the warp control means 104 may be positioned so as to hold the wire sections 101 in their straight state.

In these figures, reference numeral 113 denotes support members for the stationary shafts 98 and 114 denotes fasteners for the support members.

In the operation of the embodiment of FIGS. 13

through 17 inclusive, when the engine 90 is rotated as the entire apparatus moves to rotate the'crank 91, the roughing'mechanism 96 is caused to oscillate vertically thereby to cause the lower ends 10lb of the wire sections 101 to strike against the surface of a particular pavement 115 (FIGS. 19 and 20).

The striking stroke of the wire sections 101 will be now described referring to FIG. l7.In this figure, the solid line represents the state at the initiation of the striking stroke by the wire sections 101 toward the pavement surface 115, the one dot chain line represents the state when the lower ends 10lb of the wire sections 101 are in their lowest position or striking force delivery position and the two dot chain line represents the state in which the wire sections age in the fully retracted position of the Wi e sect-ionsIOI or the position ready for a next cycleof striking operation.

The crank shaft 97 is adapted to rock describing a locus as shown with the arrow a in FIG. 17 as the entire apparatus moves along the pavement surface 115 and the transverse shafts 100 on which the support arms 99 are mounted move in substantially parallel to the pavement surface 115 as the main body 88 of the entire apparatus moves along the pavement surface. The resiliency of the wire sections 101 is of such a degree that when the lower ends 101a of the wire sections 101 are not in contact with the pavement surface 115, the wire sections maintain their straight state by both thier own 7 restoring force to the straight state and the resiliency of the springs 111.

The roughing mechanism 96 or more particularly, the striking stroke of the wire sections 101 are so set that the lowerends 101a of the wire sections 101 contact the pavement surface 115 in the angular position of the crank shaft 95 ranging from about l/4 l/2 of one complete rotation from the uppermost position thereof in the striking or downward stroke. Therefore, the lower ends 101a of the wire sections 101 maintain their straight state at an angle with respect to the advancing direction of the apparatus until they strike against the pavement surface 115 whereupon the wire section lower ends slightly pierce into the surface and warp as shown with the one dot chain line in FIG. 17. At such a time, the warp control bars 104 are moved in proportion of the particular warping degrees of the wire sections 101 against the force of the springs 111.

Thereafter, when the roughing mechanism 96 initiates its upward movement, the wire sections 101 are instantly allowed to be restored to their straight state because the warp control means 104 are pushed bythe restoring force of the wire sections themselves and the force of the springsand the wire sections are then ready for a next cycle of striking'stroke.

In the absence of such warp control means 104 which are adapted to be urged to a predetermined position by the springs 1 11, when the osscilatory roughing mechanism 96 which has a frequency higher than the inherent frequency of the wire sections 101 is osscillated, there is the possibility that the wire sections are forced to strike against the pavement surface 115 before they can be restored their straight state after the completion of the previous striking stroke resulting in substantial lowering of the striking force. Furthermore, when the force of the springs 111 which urges the warp control means 104 is suitably adjusted, the force required to warp the wire sections 101 can be varied. Variation in the warping force makes it possible to adjust the striking force of the wire sections.

As described hereina'bove, in the embodiment of FIGS. 13 through 17 inclusive, since the wire sections 101 are restored to their straight state immediately after their striking against the pavement surface 115 by means of the warp restoring means 104, the striking can be effected with a high frequency. Thus, the pevement treating operation can be satisfactorily performed while the entire apparatus is moving at a relatively high speed along the pavement surface 115 resulting in high operation efficiency. Therefore, the roughing or slippage prevention treatment can be effected on even a pavement where traffic is heavy without obstruction of movementfor other vehicles on the pavement. And since the adjustment of the striking force can be simply made, by the employment of the pavement treating apparatus of the invention, the surfaces of various types of pavements such as asphalt pavements. concrete pavements and the like or pavements having different abrasion degrees can be renovated to their satisfactory traffic conditions.

In the first embodiment as described hereinabove, the chisels having pointed tips are employed as the roughing elements, but such chisels tend to form coarse and rugged pavement surfaces to the extent that the tire treads will not satisfactorily contact areas on the pavement. Therefore, if the coarse pavement surfaces are made finer to sandpaper-like abrasion surfaces, such sandpaper-like surfaces would satisfactorily resist slippage.

According to the present invention, it has been found that when the pavement surface is continuously or intermittently struck by the steel wires sections formed of piano wire as shown and described in connection with the second and third embodiments, the pavement surface would present a particular fractured stone appearance. Furthermore, it has been found that if the pointed tips of the chisels as shown in the first embodiment, a sandpaper like surface appearance could be obtained. Referring now to FIG. 18 which shows a modification of one of the chisels as shown in the first embodiment. In this figure, reference numeral 29 denotes a hardened chisel substantially similar to that shown in the first embodiment and has the flattened points tip 34 having a width ranging from 2 3 mm. and a weight ranging from about g. When the chisel is allowed to drop onto a rock from the height of about I mm., a fracture having the depth of about 1 mm. and an area slightly wider than the pointed tip 34 of the chisel is formed in the rock. When the same chisel 29 is allowed to drop onto a cement paved road from the same height, a fracture having substantially the same depth, but a substantially wider area than the pointed tip 34 of the chisel is formed and the surface of the cement layer is removed. Similarly, when the same chisel is al lowed to drop onto an asphalt paved road. the pointed tip of the chisel pierces into the asphalt surface layer of the pavement until the tip strikes against the aggregate lying below the surface whereupon the invasion of the chisel tip is stopped. ln this case, a recess having the depth of about 34 mm. is formed in the pavement sur face depending upon a particular blending proportion of asphalt and concrete materials. In the case of the asphalt paved road, if the chisel 29 is repeatedly allowed to drop onto the surface at successively adjacent areas thereof, the asphalt surface at such areas can be removed.

The roughing process as described just above will be in detail described referring to FIGS. 19 and 20 in which an example for roughing a particular asphalt paved road is shown. FIG. 19 shows the asphalt pavement 115 in a slippery state before the slip prevention treatment of the invention is initiated. Generally, it has been recognized that when a' certain time period has elapsed after the application of asphalt onto a pavement, the surface 117 of the aggregate comprising crushed pieces rock and gravel in the asphalt layer 1 18 will wear away and present a slippery surface to the pavement having a low coefficient of friction. When such a slippery surface is roughed by the employment of a plurality of the chisel 29 as shown in FIG. 19, the material between the rock pieces and/or gravel is removed to form a plurality of small area fractures 119 to expose the aggregate 1 16 to the newly formed pavement surface 115 as shown in FIG. 20.

As clear from the foregoing description on the preferred embodiments of the present invention, according to the present invention, the pavement surface roughing process is successively effected on successive areas along a particular pavement as the vertically movable roughing mechanism including metal roughing elements in the form of chisels, pawls, piano wire sections or the like so as to form a plurality of fractures in the worn and slippery surface of the pavement and as distinguished from the conventional pavement roughing processes which have to remove the surface material substantially deep into the surface layer to shorten the service life of the pavement. According to the present invention, a rough or slippage prevention pavement surface which has the same as or higher coefficient of friction than the pavement surface prior to the roughing treatment can be uniformly formed at a relatively less expense.

As distinguished from the conventional pavement surface roughing processes in which slippage prevention mixture material or chemical is applied onto a worn and slippery pavement surface to renovate the worn pavement, the present invention does not require such an additional material. Thus, the present invention can attain the intended purpose at a relatively less expense only requiring movement of the roughing apparatus at a constant rate along a particular pavement. Therefore, the present invention can rough the pavement surface in a relatively short period of time without requiring the obstruction of movement of other vehicles even on a heavy traffic pavement.

Furthermore, since the pavement roughing can be simply performed at a less expense, the present invention can maintain a pavement surface at a high coefficient of friction and will greatly contribute to the field of industry.

While several embodiments of the present invention have been shown and described in detail it will be unfor vertical and reciprocal movement upon application of power from said transmission mechanism soas to strike against said pavement surface to rough the surface, said roughing mechanism comprising a base guide plate having a plurality of through holes, an upper adjustable guide plate positioned above said base plate and having a plurality of through holes in staggered relationship to said holes in the base plate, a plurality of resilient wire sections extending through said holes in the base and upper plates and an anchoring plate positioned above said adjustable upper plate for anchoring one end of said wire sections.

2. The pavement surface treating apparatus as set forth in claim 1, in which said adjustable upper plates is adjustable in the vertical relative to said base plate.

3. The pavement surface treating apparatus as set forth in claim 1, in which said wire section anchoring plate is adjustable in the horizontal direction.

4. The pavement surface treating apparatus as set forth in claim 1, in which said wire sections pass through holes formed in upper and lower movable parallel shafts.

5. The pavement surface treating apparatus as set forth in claim 4, in which said upper movable shafts are Wire warp control bars. 

2. The pavement surface treating apparatus as set forth in claim 1, in which said adjustable upper plates is adjustable in the vertical relative to said base plate.
 3. The pavement surface treating apparatus as set forth in claim 1, in which said wire section anchoring plate is adjustable in the horizontal direction.
 4. The pavement surface treating apparatus as set forth in claim 1, in which said wire sections pass through holes formed in upper and lower movable parallel shafts.
 5. The pavement surface treating apparatus as set forth in claim 4, in which said upper movable shafts are wire warp control bars. 